1. Field of the Invention
The present invention relates generally to reducing power consumption in a portable device capable of receiving Global Navigation Satellite System (GNSS) signals, and more particularly, to minimizing battery usage in a portable device having a GNSS receiver being used for navigation.
2. Description of the Related Art
Satellite navigational systems provide positional and timing information to earth-bound receivers. Each system has its own constellation of satellites orbiting the Earth, and, in order to calculate its position, a receiver on Earth uses the satellites “in view” (i.e., in the sky above) from that system's constellation. Global Navigational Satellite System (GNSS) is often used as the generic term for such a system, even though such navigational satellite systems include regional and augmented systems—i.e., systems that are not truly “global.” The term “GNSS,” as used herein, covers any type of navigational satellite system, global or not, unless expressly indicated otherwise.
The number of GNSS systems, both planned and presently operational, is growing. The widely-known, widely-used, and truly global Global Positioning System (GPS) of the United States has been joined by one other global system, Russia's GLObalnaya NAvigatsionnaya Sputnikovaya Sistema (GLONASS), and is presently being joined by Europe's Galileo and China's BeiDou (also known, in its second generation, as COMPASS) systems—each of which has, or will have, its own constellation of satellites orbiting the globe. Regional systems (those that are not global, but intended to cover only a certain region of the globe) include Japan's Quasi-Zenith Satellite System (QZSS) and the Indian Regional Navigational Satellite System (IRNSS) currently being developed. Augmented systems are normally regional as well, and “augment” existing GNSS systems with, e.g., messages from ground-based stations and/or additional navigational aids. These include the Wide Area Augmentation System (WAAS), European Geostationary Navigation Overlay Service (EGNOS), Multi-functional Satellite Augmentation System (MSAS), and GPS Aided Geo Augmented Navigation (GAGAN). Regional GNSS systems, such as QZSS, can also operate as augmented systems.
Moreover, GNSS capabilities are no longer limited to any particular type of system or device. A GNSS receiver may be implemented in a cellular phone, a tablet computer, a camera, a portable music player, and a myriad of other portable and/or mobile personal consumer devices, as well as integrated into larger devices and/or systems, such as the electronics of a vehicle. The term “GNSS receiver” as used herein, covers any such implementation of GNSS capabilities in a device or system.
When a GNSS receiver is implemented in a portable and/or mobile device which relies upon one or more batteries for power, the components used for GNSS signal reception, signal processing, and positional calculation use a substantial amount of power. This is true even when the GNSS capability is only being used to compute a single position fix, such as, for example, when a cell phone user uses an application to find nearby restaurants or stores, or to view local real estate information. The tracking of a portable/mobile device with GNSS capabilities is an even bigger drain on battery resources. When the GNSS capability is being used for continuous updating of positional information, such as when navigating a route in a moving vehicle or while walking in unfamiliar terrain, it is a particularly large drain on the one or more batteries, potentially resulting in the one or more batteries not lasting until the end of the route being navigated.
Thus, there is a need for a system, method, and/or apparatus to reduce the power consumption of the one or more components used to provide a GNSS capability in a portable device powered by one or more batteries.